Vertical lift bridge



May 12, 1936. T A 'AM T 2,040,445

VERTICAL LIFT BRIDGE Filed Nov. 11, 1933 IN V EN TOR. gaw'ymm A TTQRNEYS.

Patented May 12, 1936 g 7 UNETED STATES PATENT OFFICE 2,040,445 VERTICAL LIFT BRIDGE Taneyoshi Sakamoto, Tokyo, Japan Application November 11, 1933, Serial No. 607,604

4 Claims. (01. 14-42) This invention relates to an improvement in type of operating arrangement, to provide special vertical lift bridges having a one side drive for motors equipped with synchronized speed reguraising and lowering the span thereof, and parlating devices. ticularly that type wherein an auxiliary counter- With the foregoing objects in view, and parweight is included adjacent to one end of the ticularly in order to obviate the mentioned disspan for assisting the main weights to fully counadvantages, the present invention has been inter-balance the weight of the span and facilitate troduced in order to provide a simple and effective raising and lowering the same. means for easily operating the span of a lift The main object of my invention is to provide bridge.

a lift bridge of the type indicated wherein the Referring again to the drawing, in Figure 1 span may be raised and lowered without danger the vertical guide towers l and 2 have a vertically of tilting, by means of a single unit of hoisting movable span 3 disposed between the same in machinery installed in one of the hoisting towers such manner as to be guided by said towers durof said bridge, thus reducing the cost of 'installaing raising or lowering of said span. A supporttion and upkeep to a minimum. ing cable 4 is anchored at 5 to the upper portion Other objects and the various advantages inof tower I upon the left side of Figure 1 and is herent in the structure and operation of my inpassed beneath a roller 6 adjacent to the left end vention will appear more fully in detail as this of span 3, said cable being passed directly to the specification proceeds, right along the span over a second roller 1 at In the accompanying drawing forming part the right end of the span and thence downwardly hereof, Figure 1 is a side elevation of a vertical into the foundation of the right hand tower 2 lift bridge made according to the invention and where it is anchored. In order to support the embodying its salient features in practical form. cable 4 along the distance from one of the sheaves Figure 2 is a modification of the invention with or rollers 6 to the other at I, a pair of supporting reference to the arrangement of one of the cables rollers 8' are arranged along in spaced positions thereof. to form cable guides or supports, the main guide Figure 3 is a diagrammatic view of the opersheavesbeing, of course, 6 and I. ating parts of Figure 1 in a drawn out form to v Inasmuch as both ends of cable 4 are anchored.

more fully illustrate the relations of the parts as it is but necessary to support the'right hand end well as their general arrangement and operation. of the span by means of a counterweight or an Throughout the views, the same reference nuoperating cable or any other suitable means and merals indicate the same or like parts. cable 4 will serve to maintain the span in hori- In vertical lift bridges without overhead fixed zontal position at any level of said span. span between the tops of the towers, it has here- This function is in great part served by two tofore been the usual practice to place the opercounter-balancing weights I3 and M, which toating machinery on the movable span so that the gether are intended to almost completely countertotal weight of the operating machinery would balance the weight of the span, the weight l3 be carried on the movable span, resulting in a being connected by a cable l5 over a guide sheave greater load for the span and consequently, a ll upon the left tower I to the left portion of greater load for the operating machinery and the span, while weight I 4 has a cable connecting which, in turn, would result in the increased cost the same over a sheave l8 upon the right hand of the structure as compared with a bridge with tower 2 to the right end of the span. If weight no operating machinery on the movable span. M were sufiiciently heavy to substantially coun- In another type of vertical lift bridge also ter-balance span 3 the counterweight l3 and its without any overhead fixed span, the operating cab-1e I5 would be practically superfluous as cable machinery is placed in the tower or on the founda- 4 would prevent the tilting of the span in a countion on both sides of the movable span in .order ter-clockwisedirection in view of the location of to avoid adding the dead weight of the machinery said cable beneath sheave 6 and over sheave I to. the movable span. Naturally, such arrangeof the span, but in practice it has been found ment would not only increase the cost of the to provide more smooth and reliable operation to operating machinery but also introduce certain divide the weight into two units l3 and [4 as difficulties in operating the two units of the opershown.-

ating machinery in exact synchronism so that A sub-counterweight of relatively smaller cathe span may be lifted or lowered in an exactly pacity than either weights [3 and I4 is suspended balanced condition. It is customary in such a by a cable 20 which passes over sheave 2| down r tract; the weight of the auxiliary counterweight to a winding drum I2 and from this drum the cable passes upwardly as an operating cable 9 over a sheave II and then over another sheave I upon tower 32 down to the right hand end of span 3. The operating cable 9 is secured to the winding drum I2 so that rotation of the latter terweight I9 is designed to complement the weight of'said main counterweights sufficiently to fully counter-balance the span, with the result that the weights and the span will be in a truly balanced condition. In order to facilitate the guidbf allowing the sub-counterweight to beadded' ing of the span by means of towers I and 2, the

guide rollers 22, 22 are provided upon both ends of said movable span.

j *From the foregoing it will be evident that if winding drum I2 isrotated in a clockwise direce tion the'sub-counterweight I9 will belowered while simultaneously servingto keep the cable 20 taut and also the hoisting cable 9, the latter in passing over sheaves I0 and II raising span 3 a corresponding distance to. that through which .weight I9 is lowered; Obviously, when the movable" span 3 rises, both the main counterweights I3, and I4 will also descend simultaneously with sub-counterweight I9'because cables I5 and I6 passing over sheaves II and I8 upon the towers land 2 will allow gravity to act upon said weights. It is likewise true that when the winding drum I2 is rotated'by hand or by mechanical means in acounter- -clockwise direction the span will de-v scend between towers I and 2 because the winding cable 9 will be played out from drum I2 over sheaves I0 and II down to the span, while cable 29, will draw said counterweight I9 upwardly by direct mechanical force exerted by said. wind;

fling drum, the force of gravity acting upon the span causing the same to overcome the combined weight of weights I3 and. I4 because the effect of the sub-counterweight I9 is thus removed by the deliberate operation" ofdrum I2 by raising the latter weight. g In other words, the winding drum has the effect to the -main counterweights so as to counterbalance the movable span by rotating saidwind-v ing drum clockwise, when it will be found that only a trivial amount of power will be required to raise the span, while saidc drum if rotated in a counterclockwise direction'will immediately subthe same to descend exact correspondence with the amount of cable played out from drum I2 during such counterclockwise rotation, the lowering of said span drawing the cables I5 ;and I6 from sheaves I! and I8 downwardly with the span and thus raising the main weights I3 and I4. p-It will be obvious'from the description of the operation of the bridge as illustrated in Fig. 1 and also diagrammatically shown in'Fig. 3 that in every position of the movablespan 3 the same is counter-balanced by weights I3 and I4, to,- gether with the sub-counterweight I9, while the operation of the winding drum I2 is interposed to allow the weight of the sub-counterweight to be added to or removed from association with the weightof themain counterweights I 3 and tained in a taut condition by means of the subcounterweight so that movement of the winding cable 9 and corresponding raising or lowering of the movable span 3 will be prompt and immediately responsive to rotation of drum I2 in either direction.

In addition to the foregoing, it is also true that the described arrangement of the counterweights and their cables in the present type of lift bridge provides a greater safety of operation than that of any conventional arrangement of counterweights, cables and the like in case the main on the main counterweight I4 to add its own weight thereto, so that the movable span would in any case be entirely in a balanced condition and'could be brought to rest at any position along the guide rails of the guide towers.

In view of the fact that the winding drum is disposed in one of the towers of the lift bridge and is thus in a position to control the move:- ments of the movable span by means of thehoisting cable 9 as described, it is, of course, only necessary to have one unit of hoisting machinery installed in said one tower for the purpose of operating the bridge and this is a decided'ade vantage and economy. It is, of course; at no time necessary to install the hoisting machinery upon the span itself or in both of the towers or. their hoisting cable should break. If said main cable should break, the sub-counterweight I9 would fall foundations but solely-in one of the towers or in r the foundation thereof by virtue of the presence of the sub-counterweight I9 and its connection with the hoisting cable and span 3. H

In Figure 2 is shown a modification wherein the auxiliary operating or supporting cables 4 and 4' are wound around a pair of drums 23 and 23 reg over supports or guides 8, the shaft 24 forms the connecting link which provides thesame .rela-; tion between the ends of the cable and the ends of the span and a similar control ofthelatter as the arrangement of cable 4, sheaves 6' and I andspan 3 in Figure 1. In other respects the cables and counterweights, as well as the sub-.- counterweight and the operation on the whole, is thesame as before.

. 'While I have shown and described but one or two forms of my invention and have not defi' nitely detailed the construction of the'towers and any other conventional parts, it is obvious Having now fully'described my in'vention', I'

claim: 7 e

1. In a vertical lift bridge of the character described wherein the bridge is provided with a pair of spaced towers, a movable span'disp'osed between said towers and having a roller at each end, a cable fixed at one end to the upper portion of one tower and passing beneath the roller 'onthe movable sp'an adjacent to said' tower and over the roller at the other end of the span and hav-'- ing the other end'fixed adjacent to the lower por tion of the second tower at said other end of said span, and at least one counterbalancing cable secured to said other end of the span and passed over a sheave upon said second tower, the feature of having a counterbalancing weight upon said counterbalancing cable which is insuflicient to counterbalance the dead weight of said span, a hoisting drum, a hoisting cable also secured to said other end of the span and passed over a sheave upon said second tower and about said hoisting drum, and a sub-counterweight designed to complement said first counterweight in completely counterbalancing said span and suspended upon the end of said hoisting cable which extends from said hoisting drum.

2. A vertical lift bridge according to claim 1, wherein the sub-counterweight is suspended in the second tower in a position above the counterbalancing weight upon the counterbalancing cable in said tower in order to cause said subcounterweight to drop and rest upon said counterweight in case the hoisting cable breaks.

3. A vertical lift bridge according to claim 1, wherein there are two counterbalancing weights individually suspended upon cables connected to both ends of the movable span, which two weights together are insuflicient to counterbalance the dead weight of the span, and wherein the subcounterweight supplements the weight of both said counterbalancing weights so that the aggregate weight of all three weights counterbalances the dead weight of the span.

4. A vertical lift bridge according to claim 1, wherein there are two counterbalancing weights individually suspended upon cables connected to both ends of the movable span, which two weights together are insuflicient to counterbalance the dead weight of the span, and wherein the subcounterweight supplements the weight of both said counterbalancing weights so that the aggregate weight of all three weights counterbalances the dead weight of the span, the sub-counterweight being suspended in the second tower in a position above the counterbalancing weight upon the counterbalancing cable in said tower in order to cause said sub-counterweight to drop and rest upon said counterweight in case the hoisting cable breaks.

TANEYOSHI SAKAMOTO. 

